Project Summary/Abstract Attention-deficit/hyperactivity disorder (ADHD) is among the most common reasons for childhood mental health referral with a prevalence of 7.8-11%. Despite progress in the domains of basic and translational science, diagnosis and treatment of ADHD remain controversial, etiologies remain uncertain, and clinical prediction remains poor. A multi-method approach to examine mechanisms underlying the disorder is needed to inform both etiological studies and clinical planning. Although ADHD has often been conceptualized as a cognitive disorder with emphasis on attention, executive function, and temporal processing, work by the applicant and others has established the need to integrate emotion regulation into conceptualization of the disorder and clinical care. The ultimate goals of the proposed research and training activities are to develop an independent program of research examining emotion regulation in youth with ADHD, while utilizing multiple methods and tapping into multiple levels of analysis, including behavioral, as well as autonomic and central nervous system functioning. The applicant is already well-versed in behavioral and autonomic levels of analysis as these factors relate to emotional functioning in ADHD. Thus, the proposed training emphasizes skill development in: 1) neuroimaging (i.e., fMRI) task development and data acquisition 2) neuroimaging (i.e., fMRI) data processing and analysis, 3) advanced statistical analysis, 4) training in ethics and professional development. The proposed study seeks to examine the individual and combined effects of emotion regulatory systems (i.e., behavioral, autonomic and central nervous systems) across the domains of negative emotion, positive emotion, and effortful emotion regulation in ADHD. 120 child participants (70 with ADHD; aged 7-12 years) will complete an emotion induction and regulation task (EIRT). Participants will complete the EIRT while in an fMRI scanner with electrocardiogram and respiratory activity are recorded continuously (to index autonomic nervous system activity). This acquisition of this data will allow the applicant to address two inter-related aims, including to: Examine implicit (i.e., automatic, emotion reactivity) regulation of both negative and positive emotion (Aim 1), Examine explicit (i.e., effortful) emotion regulation of both negative and positive emotion (Aim 2) in youth with and without ADHD. These aims will be able to be addressed at multiple levels of analysis. The ultimate goal of this work over time will be to help sharpen psychiatric nosology and provide improved clinical diagnosis, characterization, and prediction, while also moving psychology and psychiatry toward more personalized approaches to treatment and to spur novel interventions.